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Biomedical subjects

A Bernardo

Publications and source records attributed to A Bernardo.

At least 19 recordsLinked to original sources

Modelling thermal inactivation of Listeria monocytogenes in sucrose solutions of various water activities.

The heat resistance of Listeria monocytogenes was determined in sucrose solutions with water activity (a(w)) ranging from 0.99 to 0.90. At all temperatures investigated shape of the survival curves depended on the a(w) of the treatment medium. The survival curves for a(w)=0.99 appeared to be linear, for a(w)=0.96 were slightly upwardly concaved and for a(w)=0.93 and 0.90 were markedly concave upward. A mathematical model based on the Weibull distribution provided a good fit for all the survival curves obtained in this investigation. The effect of the temperature and a(w) on the Weibull model parameters was also studied. The shape parameter (p) depended on the a(w) of the treatment medium but in each medium of different a(w) the temperature did not have a significant effect on this parameter. The p parameter followed a linear relationship with a(w). The scale parameter (delta) decreased with the temperature following an exponential relationship and increased by decreasing the a(w) in the range from 0.99 to 0.93. However the delta parameter of survival curves obtained at a(w)=0.90 were lower than those obtained at a(w)=0.93. A mathematical model based on the Weibull parameters was built to describe the joint effect of temperature and a(w) on thermal inactivation of L. monocytogenes. This model provides a more complete information on the influence of the a(w) on the L. monocytogenes than the data initially generated. The model developed indicated that the effect of the a(w) on the thermal resistance of L. monocytogenes varied depending upon the temperature of treatment.

Colony Count, Microbial↗

Platelet-derived VWF-cleaving metalloprotease ADAMTS-13.

The adhesion ligand von Willebrand factor (VWF) is synthesized and stored in vascular endothelial cells and megakaryocytes/platelets. As in endothelial cells, platelet VWF also contains ultra-large (UL) multimers that are hyperactive in aggregating platelets. ULVWF in platelet lysates of thrombin-stimulated platelets was only detected in the presence of EDTA, suggesting that ULVWF is cleaved by a divalent cation-dependent protease. A recent study shows that platelets contain the VWF-cleaving metalloprotease ADAMTS-13, but its activity remains unknown. In this study, we show that platelet lysates cleave endothelial cell-derived ULVWF under static and flow conditions. This activity is inhibited by EDTA and by an ADAMTS-13 antibody from the plasma of a patient with acquired TTP. ADAMTS-13 was detected in platelet lysates and on the platelet surface by four antibodies that bind to different domains of the metalloprotease. Expression of ADAMTS-13 on the platelet surface increases significantly upon platelet activation by the thrombin receptor-activating peptide, but not by ADP. These results demonstrate that platelets contain functionally active ADAMTS-13. This intrinsic activity may be physiologically important to prevent the sudden release of hyperactive ULVWF from platelets and serves as the second pool of ADAMTS-13 to encounter the increase in ULVWF release from endothelial cells.

ADAM Proteins↗

Self-management of oral anticoagulation in nonvalvular atrial fibrillation (SMAAF study).

UNLABELLED: Most patients with atrial fibrillation are at risk of suffering thromboembolic events. This risk can be reduced by twothirds by efficient anticoagulation. This prospective multi-center trial investigated whether the quality of treatment can be improved by self-management in patients with atrial fibrillations (SMAAF Study) compared to conventional patient management by the family doctor. METHODS: Two thousand patients suitable for self-management were to be randomized into the two arms of the study. In the period of investigation from December 1999 to July 2001, only 202 patients (64.3+/-9.2 years, 69.3% men) consented to participate. The study was discontinued prematurely since the number of patients was too low. As a consequence, the group comparison is confined to the evaluation of the INR values measured using the two-tailed t test. RESULTS: Of the 202 patients included, 101 were assigned to the self-management group (64.6+/-9.6 years, 71.4% men) and 101 (64.1+/-8.9 years, 61.4% men, n.s.) were assigned to the group managed by the family doctor. The total number of INR measurements was 2 865. This comprised 2 072 measurements in patients under self-management and 793 in the family doctor group. The values were within the target range significantly more frequently (p=0.0061) in patients under self-management (67.8%) as compared to the family doctor group (58.5%). There was a trend with regard to the time within target range, but the difference was not significant (178.8+/-126 days as compared to 155.9+/-118.4 days). In the self-management group, there were two severe hemorrhages, and there was one thromboembolic event in the family doctor group. CONCLUSION: Management of oral anticoagulation by INR self-management in patients with atrial fibrillation is not inferior to conventional care.

Administration, Oral↗

Platelets adhered to endothelial cell-bound ultra-large von Willebrand factor strings support leukocyte tethering and rolling under high shear stress.

Leukocyte rolling on vascular endothelium is mediated by an interaction between P-selectin expressed on endothelial cells and P-selectin glycoprotein ligand-1 on leukocytes. This interaction reduces the velocity of leukocyte movements to allow subsequent firm adhesion and transmigration. However, the interaction has so far been observed only under low venous shear stress and cannot explain the accumulation of monocytes in atherosclerotic plaques found in arteries, where shear stress is much higher. We have previously shown that newly released ultra-large von Willebrand factor (ULVWF) forms extremely long string-like structures to which platelets tether. Here, we investigated whether platelets adhered to ULVWF strings are activated and form aggregates. We also determined whether activated platelets on ULVWF strings can support leukocyte tethering and rolling under high shear stresses. We found that platelets adhered to ULVWF expressed P-selectin and bound PAC-1, suggesting their rapid activation. We also found that leukocytes tethered to and rolled on these platelet-decorated ULVWF strings, but not directly on endothelial cells, under high shear stresses of 20 and 40 dyn/cm(2) in a P-selectin dependent manner. These results suggest that the endothelial cell-bound ULVWF provide an ideal matrix to aggregate platelets and recruit leukocytes to endothelial cells under high shear stress. The observed phenomenon delineates a mechanism for leukocytes to be tethered to arterial endothelial cells under high shear, providing a potential link between inflammation and thrombosis.

Adult↗

ADAMTS-13 activity in plasma is rapidly measured by a new ELISA method that uses recombinant VWF-A2 domain as substrate.

The metalloprotease ADAMTS-13 cleaves von Willebrand factor (VWF) at the Y842/M843 peptide bond located in the A2 domain. Measurement of ADAMTS-13 activity is a clinical utility for thrombotic diseases, but the current assays used for diagnostic and clinical research are non-physiological and time consuming. We have expressed in bacteria a recombinant VWF-A2 peptide (aa 718-905) that contains both a 6xHis tag at the N-terminal end and a Tag-100 epitope at the C-terminal end. Diluted plasma was mixed with the VWF-A2 peptide and digestion was allowed to proceed in a Ni2+-coated microtiter well plate for 2 h. The immobilized Ni2+ captures the VWF-A2 peptide by its 6xHis tag and cleavage of the A2 peptide is measured by the removal of the C-terminus fragment of the A2 peptide that contains the Tag-100. The cleavage activity for this assay was defined by the low detection of A2 peptide containing the Tag-100 epitope by the antiTag-100 monoclonal antibody. The assay was completed in <5 h. We then used the assay to analyze ADAMTS-13 activity in plasma from 39 healthy donors and 16 samples from patients diagnosed as thrombotic thrombocytopenic purpura. The average of enzyme activity +/- SEM for normal plasmas diluted 1 : 50 was 40 +/- 4.2% while the value obtained for the patients was 2.4 +/- 0.7%. These results were validated by a traditional long incubation assay (24 h). Our assay provides significant advantages over currently used assays because it is quicker, reproducible, cost effective and measures ADAMTS-13 activity under physiological and non-denaturing conditions. This assay is clinically useful and significant in measuring ADAMTS-13 activity in plasma.

ADAM Proteins↗

Von Willebrand factor present in fibrillar collagen enhances platelet adhesion to collagen and collagen-induced platelet aggregation.

We examined the basis of the differences observed between different collagen preparations in their ability to aggregate platelets and support their adhesion under flow. As in previous studies, we found fibrillar collagen to be 10-fold more potent than acid-soluble collagen in inducing platelet aggregation and found that acid-soluble collagen did not support the adhesion of washed platelets under flow. Further, platelets in whole blood adhered to surfaces coated with either fibrillar or acid-soluble collagen, but thrombi formed faster and grew larger on fibrillar collagen. As a possible basis for this difference, we found that fibrillar collagen, but not acid-soluble collagen, contains a substantial quantity of von Willebrand factor (VWF), as demonstrated by enzyme-linked immunosorbent assay and by the ability of fibrillar collagen to support the adhesion of VWF antibody-coated beads and to agglutinate GPIb-IX-V complex-expressing Chinese hamster ovary cells. Supporting a role for VWF in collagen-induced platelet aggregation, aggregation induced by acid-soluble collagen was greatly enhanced by added VWF. Further, platelet aggregation by fibrillar collagen was partially blocked by a GPIbalpha antibody that inhibits the GPIb-VWF interaction. Taken together, these results suggest that much of the difference in prothrombotic potency of different collagens is directly related to their differences in VWF content. This probably accounts for the different conclusions made regarding the relative importance of different direct and indirect collagen receptors in collagen-dependent platelet functions and further emphasizes the close synergistic roles of the GPIb-IX-V complex and the collagen receptors GPVI and alpha2beta1 in supporting platelet adhesion.

Cells, Cultured↗

Variations among normal individuals in the cleavage of endothelial-derived ultra-large von Willebrand factor under flow.

von Willebrand factor (VWF) freshly released from endothelial cells is normally cleaved by the ADAMTS-13 metalloprotease to prevent the direct release of these ultra-large (UL) and hyper-reactive multimers into plasma. The balance of ULVWF proteolysis may be regulated by the amount of ULVWF released and the processing capacity of ADAMTS-13. The former associates with the size of ULVWF storage pool, sensitivity of vascular endothelial cells to stimulation, and the type of agonists, whereas the latter associates with the activity of ADAMTS-13. These parameters may vary significantly among individuals. We have determined the variations of ADAMTS-13 activity in 68 normal individuals by a flow-based assay and a static assay using ULVWF strings and recombinant VWF A2 domain as substrates, respectively. We found that the levels of ADAMTS-13 activity required to cleave the platelet-decorated ULVWF strings under flow is significantly higher than that of static assays. Normal plasma diluted to 25% significantly reduced its ability to cleave ULVWF strings under flow, whereas 2% plasma retained 48% enzyme activity in static assay. ADAMTS-13 activity varied from 33 to 100% among individuals and the variations were greater at shorter incubations of plasma with the substrate. Furthermore, the production of ULVWF from endothelial cells also varied among individuals. These results suggest that the commonly used static assays may underestimate the ADAMTS-13 activity required to cleave newly released ULVWF. They also demonstrated that the proteolysis of ULVWF may vary significantly among individuals, potentially contributing to the individual's vulnerability to thrombosis so that measurement of ADAMTS-13 may serve as a marker for TTP and other thrombotic diseases.

ADAM Proteins↗

Thermal inactivation of Enterococcus faecium: effect of growth temperature and physiological state of microbial cells.

AIMS: To provide data on the effects on culture temperature and physiological state of cells on heat resistance of Enterococcus faecium, which may be useful in establishing pasteurization procedures. METHODS AND RESULTS: The heat resistance of this Ent. faecium (ATCC 49624 strain) grown at different temperatures was monitored at various stages of growth. In all cases, the bacterial cells in the logarithmic phase of growth were more heat sensitive. For cells which had entered in the stationary phase, D70 values of 0.53 min at 5 degrees C, 0.74 min at 10 degrees C, 0.83 min at 20 degrees C, 0.79 min at 30 degrees C, 0.63 min at 37 degrees C, 0.48 min at 40 degrees C and 0.41 min at 45 degrees C were found. By extending the incubation times cells were more heat resistant as stationary phase progressed, although a different pattern was observed for cells grown at different temperatures. At the lower temperatures heat resistance increased progressively, reaching D70 values of 1.73 min for cells incubated at 5 degrees C for 50 days and 1.04 min for those grown at 10 degrees C for 16 days. At other temperatures assayed heat resistance became stable for late stationary phase cells, reaching D70 values of 1.05, 1.08 and 1.01 min for cultures incubated at 20, 30 and 37 degrees C. Heat resistance of cells obtained at higher temperatures, 40 and 45 degrees C, was significantly lower, with D70 values of 0.76 and 0.67 min, respectively. Neither the growth temperature nor the growth phase modified the z-values significantly. CONCLUSIONS: D70 values obtained for Ent. faecium (ATCC 49624) varies from 0.33 to 1.73 min as a function of culture temperature and physiological state of cells. However, z values calculated were not significantly influenced by these factors. A mean value of 4.50 +/- 0.39 degrees C was found. SIGNIFICANCE AND IMPACT OF THE STUDY: Overall results strongly suggest that, to establish heat processing conditions of pasteurized foods ensuring elimination of Ent. faecium, it is advisable to take into account the complex interaction of growth temperature and growth phase of cells acting on bacterial thermal resistance.

Colony Count, Microbial↗

The microsurgical anatomy of the cisternal segment of the trochlear nerve, as seen through different neurosurgical operative windows.

OBJECTIVE: To describe the anatomy of the cisternal segment of the trochlear nerve as seen through different neurosurgical approaches. METHODS: The cisternal course of ten trochlear nerves was observed in five cadaveric embalmed heads, through the view afforded by the median infratentorial-supracerebellar, the extreme-lateral infratentorial-supracerebellar, and the combined presigmoid-subtemporal transtentorial approaches. The relationships of the trochlear nerve with the surrounding neuro-vascular structures were analyzed. RESULTS: We identified 3 segments of the cisternal trochlear nerve: quadrigeminal, ambient and tentorial. The median infratentorial-supracerebellar approach allowed exposure of the quadrigeminal segment, including the origin of the nerve. The extreme-lateral supracerebellar and the combined presigmoid-subtemporal transtentorial approaches provided visualization of the ambient and tentorial segments of the nerve. The tentorial segment runs in a dural canal contained in the free edge of the tentorium, surrounded by its own arachnoidal sleeve. CONCLUSION: The trochlear nerve is a very delicate structure that can be easily injured during approaches to the tentorial incisura. Accurate knowledge of its anatomy as seen through different operative windows is helpful in maintaining its integrity during surgery.

Brain Diseases↗

Comparison of the acidifying activity of Lactococcus lactis subsp. lactis strains isolated from goat's milk and Valdeteja cheese.

AIMS: This work was carried out to study the acid production by Lactococcus lactis subsp. lactis strains isolated from goat's milk and goat cheese (Valdeteja variety) in order to select a suitable starter culture for industrial goat cheese manufacturing. METHODS AND RESULTS: The titrable acidity of 45 Lactococcus lactis subsp. lactis strains isolated from a home-made batch of Valdeteja cheese with excellent sensory characteristics was measured over a period of 18 h. The strains were divided into two groups depending on the acid production rate: 20 fast acid producer (F) strains and 25 slow acid producer (S) strains. The kinetic parameters (lag phase, maximum acid production rate and value of upper asymptote curve) of the acid production curves for F and S strains were significantly (P < 0.001) different. CONCLUSIONS: Significant (P < 0.001) differences between titrable acidity of F and S strains were observed after the second hour of incubation. SIGNIFICANCE AND IMPACT OF THE STUDY: An F strain acetoin producer (Lactococcus lactis subsp. lactis 470Ch2) was selected as autochthonous starter culture for industrial Valdeteja goat cheese manufacturing.

Animals↗

[Initiation of oral anticoagulant treatment: comparison between different dosage regimens of warfarin and phenprocoumon].

A high "loading dosage" is often given during initiation of oral anticoagulant treatment in order to reach sufficient anticoagulation within short time. Increased bleeding risk as well as a transient prothrombotic tendency are complications of this treatment schedule. The aim of our study was to find proper dosage regimens of phenprocoumon and warfarin allowing initiation of oral anticoagulant treatment in a short time. For 50% of the patients 7.5 mg warfarin daily resulted in stable INR values within 4 days. Patients receiving higher (10 mg) or lower (5 mg) daily dosages of warfarin or 6 or 9 mg phenprocoumon daily during the first days of therapy reached the therapeutic range significantly later. Furthermore, no significant differences of prothrombin fragment F 1+2 were observed, indicating that no enhanced thrombin formation occurred. Thus, initiation of oral anticoagulant treatment using 7.5 mg warfarin daily is a simple and safe dosage regimen.

Administration, Oral↗

Essential role for NHERF in cAMP-mediated inhibition of the Na+-HCO3- co-transporter in BSC-1 cells.

Prior studies have indicated a requirement for the PDZ domain-containing protein, Na(+)/H(+) Exchanger Regulatory Factor (NHERF), for protein kinase A (PKA)-mediated inhibition of the renal basolateral Na(+)-HCO(3)(-) co-transporter (NBC). The present studies explore the potential mechanisms by which NHERF transduces cAMP signals to inhibit NBC. In BSC-1 cells, cells that express NBC but lack NHERF, 8-bromo-cAMP (100 microm for 15 min) failed to inhibit transport until wild-type mNHERF-(1-355) was expressed. mNHERF-(116-355) containing PDZ II and C-terminal ezrin-binding sequences or a mutant unphosphorylated form of rabbit NHERF effectively transduced the cAMP signals that inhibited NBC. By contrast, mNHERF-(1-126) encompassing N-terminal PDZ I and mNHERF-(1-325), which lacks ezrin-binding, failed to support cAMP inhibition of NBC activity. NBC and NHERF did not associate with each other in yeast two-hybrid or co-immunoprecipitation assays, and confocal microscopy indicated distinct subcellular localization of the two proteins. NBC was phosphorylated in BSC-1 cells, but its phosphorylation was not increased by cAMP nor was immunoprecipitated NBC phosphorylated by PKA in vitro. Acute exposure of mNHERF-(1-355)-expressing BSC-1 cells to cAMP did not change cell surface expression of NBC. Although these results established an essential role for NHERF in cAMP-mediated inhibition of NBC in BSC-1 cells, they also suggest a novel mechanism for NHERF-mediated signal transduction distinct from that previously characterized from studies of other NHERF targets.

Animals↗

Astrocytes contribute to neuronal impairment in beta A toxicity increasing apoptosis in rat hippocampal neurons.

Astrocytosis is a common feature of amyloid plaques, the hallmark of Alzheimer's disease (AD), along with activated microglia, neurofibrillary tangles, and beta-amyloid (beta A) deposition. However, the relationship between astrocytosis and neurodegeneration remains unclear. To assess whether beta A-stimulated astrocytes can damage neurons and contribute to beta A neurotoxicity, we studied the effects of beta A treatment in astrocytic/neuronal co-cultures, obtained from rat embryonic brain tissue. We found that in neuronal cultures conditioned by beta A-treated astrocytes, but not directly in contact with beta A, the number of apoptotic cells increased, doubling the values of controls. In astrocytes, beta A did not cause astrocytic cell death, nor did produce changes in nitric oxide or prostaglandin E(2) levels. In contrast, S-100 beta expression was remarkably increased. Our data show for the first time that beta A--astrocytic interaction produces a detrimental effect on neurons, which may contribute to neurodegeneration in AD.

Alzheimer Disease↗

Brain electrical microstates in subjects with panic disorder.

Brain electrical microstates represent spatial configurations of scalp recorded brain electrical activity and are considered to be the basic elements of stepwise processing of information in the brain. In the present study, the hypothesis of a temporo-limbic dysfunction in panic disorder (PD) was tested by investigating the topographic descriptors of brain microstates, in particular the one corresponding to the Late Positive Complex (LPC), an event-related potential (ERP) component with generators in these regions. ERPs were recorded in PD patients and matched healthy subjects during a target detection task, in a central (CC) and a lateral condition (LC). In the CC, a leftward shift of the LPC microstate positive centroid was observed in the patients with PD versus the healthy control subjects. In the LC, the topographic descriptor of the first microstate showed a rightward shift, while those of both the second and the fourth microstate, corresponding to the LPC, revealed a leftward shift in the PD patients versus the healthy control subjects. These findings indicate an overactivation of the right hemisphere networks involved in early visual processing and a hypoactivation of the right hemisphere circuits involved in LPC generators in PD. In line with this interpretation, the abnormal topography of the LPC microstate, observed in the CC, was associated with a worse performance on a test exploring right temporo-hippocampal functioning. Topographical abnormalities found for the LPC microstate in the LC were associated with a higher number of panic attacks, suggesting a pathogenetic role of the right temporo-hippocampal dysfunction in PD.

Adult↗

[Sexuality in patients with coronary disease and heart failure].

INTRODUCTION: When a cardiologist is speaking about sexual disorder with a patient with coronary artery disease (CAD) or heart failure (HF) mostly the male sexual disorder is the point. Questions about sexual physical stress and the use of Viagra or MUSE are dominant in the first step. But usually sexual disorders of men and women are a challenge for the cardiologist: is there not another problem behind? Is sexual disorder only a "common symptom"? Is there a need for psychotherapy? There are patients with a "well functioning" of all sexual functions but however feeling unhappy and not satisfied because lacking in sexual fulfilling [32]. The most common questions in my opinion deal with male patients after CABG or valve replacement surgery or after myocardial infarction (MI) or percutaneous transluminal coronary angioplasty (PTCA). Those patients often are concerned about future sexual activity or about a diminished libido. Some fear of failing during intercourse. HOPEFUL PREMISE: The risk of having severe complications during sexual activity is far less than many of the patients and their partners or we the cardiologists would have expected. In only about 0.9% of patients with MI sexual activity was a likely contributor to the onset of MI [27]. Regular exercise reduces the risk of MI by sexual activity. Even in high risk CAD-patients the risk for MI or death are low with 20 chances per million per hour with known CAD [14]. THE PREVALENCE OF ERECTILE DYSFUNCTION (ED) IN POPULATION BASED STUDIES: One of the largest and longest during newer studies is the Massachusetts Male Aging Study (MMAS) asking men with an age of 40-69 years. There was a prevalence of ED (3 levels: mild, moderate, complete) of 39% in the 40 years old and of maximal 67% in men with 69 years of age [16]. Common risks for ED are lower education, diabetes, heart disease, hypertension, cigarette smoking, obesity [22]. As early as possible we should reinforce patients (or even "non-yet-patients") to adopt healthy lifestyles with more physical activity to modify risk for sexual malfunction and for heart disease as well [15]. THE FEMALE SEXUAL DYSFUNCTION (FSD): The prevalence seems to be the same as in men. The most common complaints depending upon their age include decreased libido, vaginal dryness, pain with intercourse, decreased genital sensation and difficulty or inability to achieve orgasm [5]. One of the most important problems for older women are the availability of a sexually active partner and the presence of concurrent illnesses. We should ask for sexual history in older women because the need of love and sexual intimacy does not diminish with age [25]. The risks for FSD are age related as well as para-aging: level of education, history of sexual abuse or sexually transmitted disease, the "integrity" of physical health as well as the overall state general happiness [19]. DEPRESSION AS A RISC FACTOR FOR CAD AND IMPAIRMENT OF SEXUALITY: As cardiologists know sexual dysfunction may be a risk indicator for arteriosclerosis and for heart disease or even a consequence of heart disease. Depression is meanwhile recognized as a independent risk factor for MI. But the connexion of depression and sexual dysfunction is a common problem for psychiatrists', gynaecologists', urologists' and cardiologists' consulting-hours [2, 3, 18, 20, 21, 23]. HEART FAILURE AND SEXUALITY: There is very little data available on this topic. Data are dealing with the need of information for patients and partners on the physical stress during sexual activity [33]. RISK STRATIFICATION FOR SEXUAL ACTIVITY DEPENDING ON THE CLINICAL STATUS OF HEART DISEASE: The examples for clinical status are given in a simple scheme of the Princeton Consensus Panel. Patients with low risk (the large majority of patients) can be safely encouraged to initiate or resume sexual activity or to receive treatment for sexual dysfunction. In group 2 patients with an intermediate risk should undergo cardiologic evaluation before restratification into low- or high-risk category. In the high-risk patients there is a precondition before resuming sexual activity: stabilisation by specific treatment [13]. CONCLUSIONS: Think on the sexual dysfunction when treating female and male cardiologic patients. Work together with other disciplines (gynaecology, psychiatry, sexual medicine, urology) when evaluating a treatment plan. As early as possible try to reinforce lifestyle change for risk factor modification. The absolute risk for death or MI during sexual activity is very low even in patients with known CAD.

Adult↗

Peroxisome proliferator-activated receptors (PPARs) and peroxisomes in rat cortical and cerebellar astrocytes.

Astrocytes are the most versatile cells of the neural tissue. Numerous astrocytic functions--such as protection from oxidative damage, catabolism of neuroactive D-amino acids acting as neuromodulators, synthesis and catabolism of some lipid molecules, and, possibly, gluconeogenesis--reside in peroxisomes. The expression of several peroxisomal enzymes, particularly those of the acyl-CoA beta-oxidation pathway, is regulated by a class of ligand-activated transcription factors, known as peroxisome proliferator-activated receptors (PPARs), acting on their target genes as heterodimers with the retinoid X receptors (RXRs). In this work, primary and secondary cultures of astrocytes from the cerebral cortices and cerebella of neonatal rats (2 and 7 days of postnatal age) were utilized to investigate the expression of peroxisomal enzymes, PPAR and RXR isotypes (alpha, beta and gamma), by both biochemical and immunological methods. The results obtained demonstrate that astrocytes in vitro express peroxisomal enzymes, PPARs, and RXRs and that differences dependent on brain area, animal age, and culture time are reminiscent of the in vivo situation. Therefore, primary cultures of astrocytes and, particularly, high purified subcultures may constitute a useful model for further studies aimed to gain further insights into the roles of peroxisomes and PPARs related to lipid and glucose metabolism in these cells.

Acyl-CoA Oxidase↗

Human immunodeficiency virus type-1 Tat protein induces nuclear factor (NF)-kappaB activation and oxidative stress in microglial cultures by independent mechanisms.

We have extended our previous findings and shown that human immunodeficiency virus Tat protein, in addition to nitric oxide (NO), stimulated rat microglial cultures to release pro-inflammatory cytokine interleukin-1beta and tumour necrosis factor-alpha in a nuclear factor (NF)-kappaB-dependent manner. At the same time, Tat stimulated the accumulation of free radicals, as indicated by the increased levels of isoprostane 8-epi-prostaglandin F(2alpha) (8-epi-PGF(2alpha)), a reliable marker of lipid peroxidation and oxidative stress, by a mechanism unrelated to NF-kappaB activation. The presence of free radical scavengers abrogated Tat-induced 8-epi-PGF(2alpha) accumulation without affecting NO and cytokine production. Consistently, Tat-induced IkappaBalpha degradation - an index of NF-kappaB activation - was not affected by free radical scavengers, but was prevented by an NF-kappaB-specific inhibitor. Our observations indicate that NF-kappaB plays a key role in Tat-dependent microglial activation, and that oxidative stress and NF-kappaB activation induced by Tat occur by independent mechanisms.

Animals↗